Existing broadcast mediums exist in society for purposes of news and entertainment. These mediums include various forms of digital and analog Radio, TV, Web, Public Address and even audible toys or buttons. Also, sound modulation is one of the oldest modulation methods for wireless and wired communication known to human beings, from the beating of a drum, to SONAR, to the now antiquated high speed modems. Audio was the medium of choice for digital modulation used to forge a path for the internet. Sound, and in general low frequency audible sound, has been used for man to man, man to machine and machine to machine communications. However, the capability of high frequency bidirectional acoustic transmission has only recently been made widely available in smart mobile appliances (e.g. smart phones and tablets) because of the widespread CD and DVD audio qualities of 44.1 KHz and 48 KHz sample rates rather than the more typical 8 KHz audio capability found in prior mobile equipments. With the introduction of smart mobile appliances capable of high frequency bidirectional acoustic transmission, using high frequency sound outside human hearing range as a digital modulation carrier for communication may be a software only solution that piggybacks off of the audio capabilities required for other mainstream services accomplished on the smart mobile appliances, and thus become a potential approach for communication and control of the appliances as an addition or alternate to the commonly used RF wireless modulation.
Several existing applications have been written to identify a song or an advertisement using a smart phone to first record a small portion of the audio from the song or advertisement, which is then sent to a database in the Internet cloud for comparison and matching of the lower frequency audio using pattern matching techniques (aka Fingerprinting). However, the inventor of this current invention realizes that there is value in many markets requiring not only identification of the audio being played but also the location and even the time associated with the reception of the audio by extracting digital information embedded purposefully in the high frequency portions of these broadcasts. This purposefully embedded digital in-band messaging may be applied to mark a specific location in the broadcast and/or relay usable information to control a smart mobile appliance or otherwise add or improve user experience.
Some applications have opted for the use of scanning of QR or other bar codes and in some cases, the use of NFC or RFID technology for location based services. Yet those skilled in the art can easily recognize the inherent difficulties either in the additional hardware requirements associated with RFID/NFC technology and the point/focus and lighting problems of using bar code technologies to obtain information. Further, both bar code scanning and NFC/RFID, while arguably more secure than credit cards, offer little in the way of advanced payment security, because advanced security requires real time intelligence on both sides of the transaction which is lacking in both of these competing technologies.
In contrast, using digital in-band messaging purposefully embedded in existing high frequency acoustic signals may be a simple and more secure approach to remotely control mobile communication devices. Therefore, one objective of the current invention is to accomplish this approach. In order to implement the embedded digital in-band messaging via a sound channel, effective digital encoding is needed. Digital encoding of a signal over a wave carrier (light, sound or radio) in an open environment presents many problems due to signal reflection, which can seriously attenuate the signal resulting in transmission errors and the need for complex transmitters, receivers and software drivers. Many ingenious and complex methods have been invented over the years to compensate and/or recover a signal in these environments. These methods apply mostly to the transmissions of relatively large amounts of dynamic data and mostly over radio transmissions that are undeniably useful for the purposes intended.
However, especially with the increased usage of smart mobile devices, it is believed that the need for small amounts of data bursts or continuous beacons of digital transmission is, and will increasingly be, more useful. Unfortunately, there has not been a lot of innovation in providing methods for efficiently transmitting digital information in continuous beacons to maximize efficiency and payload while minimizing complexity. This is especially true with respect to highly reflective wave transmission using digitally modulated acoustics. In contrast, acoustic digital modulation, using smart mobile devices, represents major advantages with respect to already deployed infrastructure, development cost and customer experience. Further advantages exist while using a continuous transmission envelope rather than time/space modulated message header in both radio and acoustic mobile applications for indoor location.
Therefore, another objective of the current invention is to provide an encoding method for transmission of relatively small amounts of data in a continuous or repeated manner via existing sound channel, while using as little transmission energy as possible and thus reducing development cost and increasing transmission speeds.